The complexity of the maximum common subgraph problem in partial k-trees is still largely unknown. We consider the restricted case, where the input graphs are k-connected partial k-trees and the common subgraph is req...
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ISBN:
(纸本)9783662444658;9783662444641
The complexity of the maximum common subgraph problem in partial k-trees is still largely unknown. We consider the restricted case, where the input graphs are k-connected partial k-trees and the common subgraph is required to be k-connected. For biconnected outerplanar graphs this problem is solved and the general problem was reported to be tractable by means of tree decomposition techniques. We discuss key obstacles of tree decompositions arising for common subgraph problems that were ignored by previous algorithms and do not occur in outerplanar graphs. We introduce the concept of potential separators, i.e., separators of a subgraph to be searched that not necessarily are separators of the input graph. We characterize these separators and propose a polynomial time solution for series-parallel graphs based on SP-trees.
We give an efficient encoding and decoding scheme for computing a compact representation of a graph in one of unordered reduced trees, cographs and series-parallel graphs. The unordered reduced trees are rooted trees ...
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We give an efficient encoding and decoding scheme for computing a compact representation of a graph in one of unordered reduced trees, cographs and series-parallel graphs. The unordered reduced trees are rooted trees in which (i) the ordering of children of each vertex does not matter, and (ii) no vertex has exactly one child. This is one of basic models frequently used in many areas. Our algorithm computes a bit string of length 2l - 1 for a given unordered reduced tree with l >= 1 leaves in O(l) time, whereas a known folklore algorithm computes a bit string of length 2n-2 for an ordered tree with n vertices. Note that in an unordered reduced tree, l >= n < 2l holds. To the best of our knowledge this is the first of such a compact representation for unordered reduced trees. From the theoretical point of view, the length of the representation gives us an upper bound of the number of unordered reduced trees with l leaves. Precisely, the number of unordered reduced trees with l leaves is at most 2(2l-2) for l >= 1. Moreover, the encoding and decoding can be done in linear time. Therefore, from the practical point of view, our representation is also useful to store a lot of unordered reduced trees efficiently. We also apply the scheme for computing a compact representation to cographs and series-parallel graphs. We show that each of cographs with n vertices has a compact representation in 2n - 1 bits, and the number of cographs with n vertices is at most 2(2n-1). The resulting number is close to the number of cographs with n vertices obtained by the enumeration for small n that approximates Cd-n/n(3)/(2), where C = 0.4126 ... and d = 3.5608 ... . series-parallel graphs are well-investigated in the context of the graphs of bounded treewidth. We give a method to represent a series-parallel graph with m edges in [2.5285m - 2] bits. Hence the number of series-parallel graphs with m edges is at most 2([2.5285m-2]). As far as the authors know, this is the first non-trivial r
A series-parallel graph is a graph that does not contain a complete graph with four vertices as a minor. A new explicit simpler formula for the number of labeled series-parallel biconnected graphs with a given number ...
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In this paper, we will study the adjacent strong edge coloring of series-parallel graphs, and prove that series-parallel graphs of △(G) = 3 and 4 satisfy the conjecture of adjacent strong edge coloring using the doub...
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In this paper, we will study the adjacent strong edge coloring of series-parallel graphs, and prove that series-parallel graphs of △(G) = 3 and 4 satisfy the conjecture of adjacent strong edge coloring using the double inductions and the method of exchanging colors from the aspect of configuration property. For series-parallel graphs of △(G) ≥ 5, △(G) ≤ x'as(G) ≤ △(G) + 1. Moreover, x'as(G) = △(G) + 1 if and only if it has two adjacent vertices of maximum degree, where △(G) and X'as(G) denote the maximum degree and the adjacent strong edge chromatic number of graph G respectively.
It is known that any signed series-parallel graph (G, sigma) has circular chromatic number at most 10/3. This paper proves that for each rational r is an element of [2,10/3], there is a signed series-parallel graph (G...
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It is known that any signed series-parallel graph (G, sigma) has circular chromatic number at most 10/3. This paper proves that for each rational r is an element of [2,10/3], there is a signed series-parallel graph (G, sigma) whose circular chromatic number equals r. (C) 2021 Elsevier B.V. All rights reserved.
A series-parallel graph can be constructed from a certain graph by recurslvely applying “series” and “parallel” connections The class of such graphs, which Is a well-known model of series-parallel electrical netwo...
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The strong fractional choice number of a graph G is the infimum of those real numbers r such that G is (inverter right perpendicular rm inverter left perpendicular, m)-choosable for every positive integer m. The stron...
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The strong fractional choice number of a graph G is the infimum of those real numbers r such that G is (inverter right perpendicular rm inverter left perpendicular, m)-choosable for every positive integer m. The strong fractional choice number of a family G of graphs is the supremum of the strong fractional choice number of graphs in G. We denote by Q(k) the class of series-parallel graphs with girth at least k. This paper proves that the strong fractional choice number of Q(k) equals 2 + 1/ left perpendicular(k+1)/4 right perpendicular. (C) 2019 Published by Elsevier B.V.
Let G be a graph with a single source w, assigned a positive integer called the supply. Every vertex other than w is a sink, assigned a nonnegative integer called the demand. Every edge is assigned a positive integer ...
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Let G be a graph with a single source w, assigned a positive integer called the supply. Every vertex other than w is a sink, assigned a nonnegative integer called the demand. Every edge is assigned a positive integer called the capacity. Then a spanning tree T of G is called a spanning distribution tree if the capacity constraint holds when, for every sink v, an amount of flow, equal to the demand of v, is sent from w to v along the path in T between them. The spanning distribution tree problem asks whether a given graph has a spanning distribution tree or not. In the paper, we first observe that the problem is NP-complete even for series-parallel graphs, and then give a pseudo-polynomial time algorithm to solve the problem for a given series-parallel graph G. The computation time is bounded by a polynomial in n and D, where n is the number of vertices in G and D is the sum of all demands in G.
This paper deals with single-machine scheduling problems with decreasing linear deterioration, i.e., jobs whose processing times are a decreasing function of their starting times. In addition, the jobs are related by ...
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This paper deals with single-machine scheduling problems with decreasing linear deterioration, i.e., jobs whose processing times are a decreasing function of their starting times. In addition, the jobs are related by parallel chains and a series-parallel graph precedence constraints, respectively. It is shown that for the problems of minimization of the makespan, polynomial algorithms exist. (C) 2009 Elsevier Ltd. All rights reserved.
Given a graph G = (V, E) and an integer k >= 1, the graph H = (V, F), where F is a family of elements (with repetitions allowed) of E, is a k-edge-connected spanning subgraph of G if H cannot be disconnected by del...
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Given a graph G = (V, E) and an integer k >= 1, the graph H = (V, F), where F is a family of elements (with repetitions allowed) of E, is a k-edge-connected spanning subgraph of G if H cannot be disconnected by deleting any k - 1 elements of F. The convex hull of incidence vectors of the k-edge-connected subgraphs of a graph G forms the k-edge-connected subgraph polyhedron of G. We prove that this polyhedron is box-totally dual integral if and only if G is series-parallel. In this case, we also provide an integer box-totally dual integral system describing this polyhedron.
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